Table 4.
Functional expression of the NOP receptor in rodent nociceptive system and effects of N/OFQ under conditions of inflammatory pain
| NOP receptor expression | N/OFQ function | ||||
|---|---|---|---|---|---|
| Region | mRNA | Protein | In vitro | In vivo | |
| Supraspinal | Thalamus | i.c.v.: ↑ pain response, antagonized opioid analgesia [formalin test rat] (Zhu et al., 1997; JL Wang et al., 1999a) | |||
| Amygdala | |||||
| PAG | i.c.v.: antagonized morphine analgesia [CFA inflammation rat] (Bertorelli et al., 1999) | ||||
| RVM | i.c.v.: no inhibition of colonic hyperalgesia [colorectal distension in TNBS-treated rats] (Agostini et al., 2009) | ||||
| Spinal | Intrinsic neurons | Up-regulation in L4 dorsal horn (laminae I, II) 4 days after CFA [RLB] (Jia et al., 1998) | i.t.: analgesic [formalin test rat] (Erb et al., 1997; Yamamoto et al., 1997a; Hao and Ogawa, 1998; YQ Wang et al., 1999a) | ||
| i.t.: ↓ thermal hyperalgesia, ↓ flexor reflex [carrageenan inflammation rat] (Yamamoto et al., 1997b; Hao et al., 1998; Xu et al., 1999) | |||||
| Proximal PAF (presynaptic) | ↑ inhibition of C-fibre evoked responses of spinal neurons 4h after carrageenan [in vivo electrophysiology rat] (Carpenter et al., 2000) | ||||
| Peripheral | DRG neuron (cell body) | Up-regulation at day 1 and 7 after CFA [IHC] (Chen and Sommer, 2006; 2007) | |||
| Distal PAF (dendritic) | i.v.: inhibition of articular mechanosensitivity [carrageenan-induced knee joint inflammation, rat] (McDougall et al., 2000) | ||||
| i.p.: inhibition of colonic hyperalgesia [colorectal distension in TNBS-treated rats] (Agostini et al., 2009) | |||||
No data are published for fields that are left blank. ↑, activation/increase; ↓, inhibition/decrease; IHC, immunohistochemistry; PAF, primary afferent fibre; RLB, radioligand binding.